the GM bailout, the continuing woes it's going to cause the US car industry, as well as the huge deficits for the other bail-outs, and the failed monetary policy ... someone's going to have to take the hit for it, and "the buck stops here" for a reason.
Damned if you do and damned if you don't.
If GM and Chrysler had been told to piss up a rope the fallout would likely have completely disrupted the entire global supply chain for car makers, heavy truck makers, and even heavy equipment makers. Shutting that entire sector of the economy down would have spilled over into the companies who make basic materials like steel, aluminum, glass, rubber, etc. Also into things like electronics (the auto industry is the largest customer for electronic components). Personally I'd rather have a sort of sick US auto industry than a global economic collapse.
Same thing applies to the monetary policy, if anything the danger is in not letting the "unconventional" measures run their course and trying to battle inflation and deficits way too soon.
Again if no corrective action to the financial sector had been applied and no stimulative measures taken I suspect the shape of the global recession would have been much worse.
If you think Obama's got problems because "we need to blame someone" just think of how much worse it would be if global GDP was falling twice as fast and twice as many people were out of work.
BTW I seriously doubt there will be any challenge from Hillary in 2012. She would run if Obama decides not to seek a second term, but I think that is unlikely as well. I do think Obama will be challenged by other Democrats in 2012 and some of those may be people you've heard of (current and former governors and senators). But the challengers won't be anyone in the current administration.